Cell population and utrastructural studies will be performed on lenses of animals possessing varying degrees of accommodative ability. The hypothesis to be tested is that the lens shape and its accommodative power may be determined by the quantities, types and distribution of cytoplasmic fibrous organelles. As these organelles increase in number, as in spherical lenses, and in aging cataractous lenses with high accommodative capacity, deformation of the lens becomes increasingly more difficult. It is thought that in eyes with well-developed ciliary muscle attempts to deform the lens result in increased stress within the lens; intercellular connections and plasma membranes may be ruptured, thereby initiating cataractogenesis. The inherent intension within the lens exerted by the fibrous cytoplasmic organelles may determine the kind of response of the lens to a penetrating injury, i.e., wound repair or cataract formation. Cytoplasmic fibrous organelles will be studied with the electron microscope with regard to their distribution in lenses before and after a penetrating injury and in lenses of different ages. Changes in quantities of these organelles will be assayed by SDS acrylamide gel electrophoresis, and the properties of the filamentous proteins will be determined by comparison with known protein markers.